1. Field of the Invention
The present invention relates to a traction device for performing traction with a rope, and more particularly to a traction device for medical use which is adapted for correcting an affected part of a patient having a fracture in his or her arm, leg, cervical vertebrae or the like by pulling such affected part.
2. Description of the Related Art
As a conventional traction device for medical use, one shown in FIG. 4 which is invented in Holland is known. To operate this traction device, first of all, a rope 2, which is wound around a drum 1 with one end thereof held at the drum 1, is paid out to allow the other end thereof to be attached to, e.g., a foot of a patient. Next, the drum 1 is fixed by tightening a lock handle 3. Thereafter, a spiral spring inside the drum 1 is tightened by rotating a handle 4, whereby the drum 1 is imparted a potential energy for rewinding the rope 2. Traction is thus performed as the rope 2 becomes tense due to the drum 1 being urged by the spiral spring.
In the aforementioned conventional traction device for medical use, in order to rewind the rope 2 onto the drum 1 after a fitting attached to the other end of the rope 2 has been removed from the foot of the patient, an operator is required to hold the rope 2 with his or her hand so that the 2 will be reversely wound around the drum 1 quietly. If the rope 2 is not thus held, the spiral spring inside the drum 1 pulls the rope 2 rapidly back onto the drum 1, making it likely that not only an operator such as a nurse will be exposed to danger, but also the rope 2 will be jammed on the drum 1 so that the traction device is not readily usable for subsequent operations.
It is therefore an object of the present invention to provide a traction device for use in medical therapy which is easy to operate and highly safe, and which allows a traction rope to be rewound an a drum in an orderly way.
In one aspect, the present invention provides a traction device for medical use, which comprises a drum for rewinding a traction rope while holding a tail end of the rope, a casing for rotatably supporting the drum therein, a spring for urging the drum in a direction of rewinding the rope, a rope coupling attached to a head end of the rope paid out from a rope entrance provided in the casing for blocking the pulling in of the head end of the rope, a first gear provided so as to be rotatable integrally and in a manner concentric with the drum, and a rotary damper having a second gear, which is a small reduction gear meshed with the first gear, and being installed inside the casing.
In another aspect, the present invention provides a traction device for medical use, wherein a tension meter for indicating a tension of the rope is interposed between the rope and the rope coupling.
In still another aspect, the present invention provides a traction device for medical use, wherein a roller for guiding the rope and a biasing piece for resiliently biasing the rope onto the roller are provided in the vicinity of the rope entrance provided in the casing.
In still another aspect, the present invention provides a traction device for medical use, wherein the spring is constructed of a spiral spring contained in a hollow portion of the drum, one end of the spiral spring which is located at the center is fixed to a central shaft which is loosely fitted into the drum in a manner concentric with the drum and supported on the casing, the other end of the spiral spring is fixed to an inner circumferential wall portion located in the hollow portion of the drum, and an adjusting member integrally rotatable with the central shaft for adjustably applying an initial load to the spiral spring is releasably attached to the outside of the casing.
In the above-mentioned traction device for medical use, the drum for rewinding the traction rope is coupled to the rotary damper at all times through the second gear, which is a small reduction gear meshed with the first gear that is integrated with the drum, even when the spring urges the drum in the direction of rewinding the rope. As a result, when the rope is removed from the affected part of a patient suffering a fracture, it is not likely to be drawn back onto the drum violently. Hence, the rewinding operation can be performed at such mild speeds as not to expose an operator such as a nurse to danger.
Further, since all components such as the drum and the damper are installed inside the casing, the traction device can be handled with more ease.
When the tension meter is provided between the rope and the rope coupling, the tension meter can constantly monitor the tractive force applied to the affected part of a patient, thereby allowing a desired traction condition to be maintained.
If the roller for guiding the rope and the biasing piece, which is a flat spring-like piece, for resiliently biasing the rope onto the roller are provided in the vicinity of the rope entrance provided in the casing, during the rewinding operation of the rope onto the drum after a therapy with this traction device has been completed, the damper and the reduction mechanism constructed of the gears jointly act to decelerate the rope pulling speed, and further, the additional action of the biasing piece that biases the rope onto the roller prevents the rope from whirling and bouncing. Therefore, the rope can be rewound onto the drum neatly, thereby eliminating such inconvenience that the operator will have difficulty handling the rope during the next operation.
When a spiral spring is used as the spring and is inserted into the drum, and when the adjusting member for applying an initial load to the spiral spring is releasably attached to the outside of the casing, an initial tractive force can be set properly in the order of 10 N (≈1 kgf) in advance, and hence the operator can use the traction device in hospitals in an extremely simple way.
When a ratchet plate is used as the adjusting member and the ratchet plate meshes with the rotary pawl having a spring attached thereto, the initial load can be applied to the spiral spring easily by rotating the ratchet plate intermittently.